Equalizer fob automatic player pianos



Aug. 9, 1927-. 1,638,419

0; F. STODDARD EQUALIZER FOR AUTOMATIC PLAYER PIANOS File d June l,- 1923 2 Sheets- Sheet 1 (gm/vents:

(bar/rs fjfbddard 351, M5 61mm Aug. 9, C. F. STODDARD EQUALIZER FOR AUTOMATIC PLAYER PIANO S Filed June 1, 1923 2 Sheets-Sheet 2 95 111 5 flbfiomw s Patented Aug. 9, 1927.

UNITED STATES PATENT OFFICE.

CHARLES E. STODDARD, or new YORK, N. Y., Assmnon. T AMERICAN PIANO COM- PANY, or'nnw 2031;, it. 2., e oonronarlon or new JERSEY.

EQUALIZER non AIJTOMATEC rnaxnn rmxos.

Application filed June 1,

This invention relates to automatic musi cal instruments, and more particularly to expression governing means for the sainede signed to produceaccurate and delicate govcrning of tone intensities.

voirs 4.

It isan object of this invention to'provide improved expression governing means de signed to maintain substantial uniformity of playing intensities of the instrument, and particularly the lower playing intensltles, and which may be advantageously combined with the ordinary expression governing means to cooperate therewith.

Another object of the present invention is the provision of an improved equalizing means designed to maintain 7 within itself substantially the same pressure whether it is in its extreme condition of expansion or contraction.

The accompanying drawings show an automatic musical instrument constituting a preferred embodiment of the invention selected for purposes of. illustration, in which,

Figure 1 is a semi-diagrammatic representation of a pneumatic system for an automatic player piano embodying the present invention. I

Figure 2 is a detailplan view showing the improvedequalizer bellows in collapsed position.

Figure 3 is an additional detail plan view, partly in section, showing the equalizer bellows in expanded position.

Referring to the drawings, a mam source of power is designated generally by 1 and consists of a feeder wind chest 2 and feeder bellows 3 connected thereto. Also connected to the feeder wind chest are the usual reser- The feeder bellows 3 are operated in the usual manner by pedals 5 which are 'operatively connected'thereto by the usual crank and levermechanisms 6.

The source ofpower as described may be of any of the ordinary well-known types of foot power pumpers and is therefore not further described in detail. It is to be understood, however, that the invention is not limited to a foot power pumper, but may be used with a suitable power driven pump.

Expression mechanisms for governing tone intensities are designated generally by the numeral 8 and consist of the expression wind chest 9 which, as shown is divided longitudinally by the partition 10 into two chests 11 and 12, the chest 12 being known as 1923. Serial No. 642,746,

nected by port 13, the effective opening of which is controlled by a valve 14. This valve is mounted on a valve stem 15 and is connected with a hinged board 16 by any suitable connections as 17 Also connected with this hinged board 16 are expression pneuinatics 18, 19 and 20 which are mounted on a fixed board 21. Attached to the upper end of the valve stem 15 is a tension spring 22 which may be set to' any desired tension, either manually or automatically and exerts a substantially constant upward pull on the valve stem and valve. Ifthe tension of the spring 22 is to be adjusted manually, apparatus such as that shown in Patent No. 1,409,479 of March 14, 1922, may be em ployed, while if it is desired to control the tension of said spring automatically, apparatus suchas that shown and described in Patent No. 1,409,484 of March 14, 1922, may be employed.

The valve block 23 is provided for controlling the operation .of the expression pneumatics 18, 19 and 20 and may be conveniently mounted above the expression chest 9, as shown. This block is provided with an exhaust chamber 24 which is connected by the passage 25 with the regulated wind chest 11. In the lower side of this exhaust chamber are the depressions 26, 27

and 28 which form diaphragm chambers covered by the diaphragms 29, 30 and 31. htiounted above these diaphragms, and operated thereby, are valves32, 33 and 34 which control comn'iunication of the expression ,pneumatics 18, 19 and 20, through the pas,- sages 35, 36 and 37, with either the exhaust chest 24 or with atmosphere. i

. lVhen the valves 32, and 34 are seated, as shown in Figure 1, the expression pneumatics 18, '19 and 2.0 are connected with regulated air through the passages35, 36

and 37, tho exhaust chamber 24 andtlie passage 25. Under these conditions, therefore, the valve 14 will operate to maintain a substantially uniform tension in the regulated Wind chest 11 in a well-known manner. The tension maintained will be low tension be cause under these'conditionsamaximum of regulated air is admitted to expression pneumatics 18, 19 and 20 exerting a downward pull on the valve tending to close the same. In order to provide distinct steps of intensity and thereby vary the playing intensities of the instrument, tubes 38, 39 and 40 are provided connecting the tracker 41 with the diaphragm chambers 26, 27 and 28. If the tube 38 is opened to atmospheric air by an opening in a note sheet passing over the tracker 41, the valve 32 will be raised thus cutting off the expression pneumatic 18 from regulated air and admitting atmospheric air thereto. The downward force on the valve 14 would be substantially reduced shown and described in Patent No. 1,409,494

of March 14, 1922, and will not be described in further detail here.

A wind trunk 42 is connected to the regulated wind chest 11 and is connected at. its other end to the action wind chest 43, thus maintaining therein the same tensions as those established in the regulated wind chest 11.

It is to be understood that the mechanisms thus far described may be used to control a single wind chest for the entire range of a piano. It is convenient, however, to divide the action wind chests into two sections, base and treble, which are here designated respectively by 43 and 43. Identical ex ression mechanisms to those already descri ed are provided, designated by 8', which are connected with the source of power by the wind trunk 7' and with the action wind chest 43' by the wind trunk 42'.

In communication with the action wind chest is located a low pressure equalizer, so called because, as will be hereinafter explained, the spring is so adjusted that it will only come into operation when low pressures are being maintained in the wind chest. This equalizer is connected with the wind chest 43 by suitable ports 45, the number and size of which is not material except that suflicient area should be provided to permit free flow of air. The leaf 46 of the equalizer maybe conveniently fixed to the wind chest as shown, and the movable leaf 47 is hinged thereto. The bellows is covered with the usual bellows cloth 48 as shown.

As has been set forth before somewhat generally, the valve 14 operates as a regulator to maintain in the action wind chest a substantially uniform pressure whether one or many notes be sounded. For example,

if many notes are sounded at approximately the same time, there will be a great inrus of air from the action pneumatics into the system. This will tend to reduce the tension in the regulated wind chest 11 and therefore in the exhaust chamber 24, and also in the expression pneumatics 18, 19 and 20. Valve 14 therefore would tend to rise and additional air would be withdrawn from the instrument. Under other conditions, if only a few notes are sounded less air will be admitted to the wind chest, tension will tend to increase in the regulated wind chest 11 and the expression pneumatics 18, 19 and 20 would tend to collapse. Valve 14 therefore would tend to close and less air would be withdrawn from the instrument.

The system just described operates satisfactorily at moderate intensities. On very low intensitie however, it has been found that the operation of the instrument may be improved by the provision of additional means which are only in operation during playing of such intensities.

Suppose for the present that the improved type of equalizer mechanism shown be disregarded and that a simple type of bellows pneumatic with the ordinary V spring be considered. Suppose further, that the spring be adjusted to such tension that the pneumatic will remain collapsed even when the instrument is playing lowest intensities but will open when thetension tends to dro below this point. Assume further that all of the expression neumatics are exposed to rcgulated air, so that the instrument is playing lowest intensities. If under these conditions a large number of playing pneumatics are operated, there will be a great inrush of air to the wind chest, thus tending to reduce the tension therein. The equalizer pneumatic 44 will immediately tend to expand, therefore, thus drawing air from the wind chest and tending to maintain the tension therein at a constant level.

The adjustment of the equalizer just described is important, because, if the pneumatic tends to open above lowest intensities. it would be necessary to entirely exhaust it before an accent or other inten ity change could be effected. Within the range where intensity changes are-desired then, the equalizer is inactive, while on the lowest intensity, it is active tending to maintain the tension at a constant level Whether one or many notes are sounded.

It will be seen then that the equalizer means just described acts as an additional tension maintaining device for the regulating means before described, but being in freer communication with player pneumatics will act more quickly than the regulator valve. 'lVhen bothare in operation, however, each will modify the action of the other as will be understood.

in may be desirable to provide instead of the simple bellows pneumatic, an improved type of tensioning mechanism which will serve at all times, whether the pneumatic be stantially constant tension therein. A block 49 is fixed on a movable leaf l7 of the equalizer and pivoted thereto at 50 is the link 51. Another block 52 is his sued to the fixed leaf oi? the pneumatic and a link'M is pivoted thereto at The two links 51 and 5-1 are pivotally connected at 55. A spring 56 is attached to the link 51 by a suitable projection 57 and the other end of this spring is connected to a screw 58, adjustably mounted on the block 59.

When thepneumatic is expanded it will be noted that the spring 56 is in a position to exert a maximum pull on the link 51 because it is pulling around the pivot 50 and the lever arm is at that point at a maximum. In the collapsed position showninFigure 2, the lever arm has been reduced in length and the effective pull on the link 51 is therefore correspondingly reduced. The action of the spring in the meantime, however, has been just the reverse. In the expanded position of the pneumatic the pull of the spring is at a minimum, while in a colapsed position the pull is at a maximum due .to its added distention. As the pull of the spring increases, therefore, the lever arm through which it acts decreases, thus tending to compensate the increase in the pull of the spring. Another variable force must be considered however. As the bellows collapses the ell'ective area on which pneumatic forces act is decreased due to the folding of the bellows cloth.

To sum up, three variable forces are pres ent as the bellows collapses, the spring tension incr sees, and the efiective area of the pneumatic and the lever arm through whichthe spring acts decreases. .The arrangement of the parts just described operates to cause the increase in spring tension to compensate the decrease in lever arm and area, thereby maintaining a substantially constant tension in the bellows.

It is to be understood that the invention is not limited to the illustrative embodiment herein shown and described. On the contrary, the invention may be variously moditied and embodied within the scope of the subjoined claims. 7

I claim as my invention:

1, In an automatic musical instrument having the usual striker pneumatic and source of power, in combination, an action wind chest; a regulator; and equalizing means controlling the tension in said wind chest, operative only when the tension therein falls below the lowest tension which the regulator is adjusted to maintain.

2. In an automatic musical instrument having the usual striker pneumatics; and source of power, in combination, an action wind c'liest; a regulator; and additional means to withdraw air from the wind chest expanded orcollapsed, to maintain a subwlientlie tension falls below the lowest tension which the regulator is adjusted'to maintain. V

3. In an automatic musical instrument having the usual striker pneumatics and sourceof powcr,'in combination, an action wind chest; a regulator; and a pneumatic controlling the tension in said wind chest; means for tensioning said pneumatic; and means for adjusting said tensioning means to a point such that said pneumatic will tend to open when the tension in the wind chestfalls below the lowest tension which the regulator is adjusted to maintain.

having the usual striker pneumatics and source of power, in combination, an action wind chest; a regulator; an equalizer in communication with said wind chest; and means to exert upon said equalizer an opening force substantially equal to the closing force exerted by the lowest tension within said wind chest which, said regulator is set to maintain.

5. In an automatic musical; instrument having the usual striker pneumatics and source of power, in combination, an action wind chest; a regulator; an equalizer in communication with said wind chest; and yielding mechanical means to exert upon said equalizer an opening force substantially equal to the closing pneumatic force exerted by the lowest tension within said wind chest which said regulator is set to maintain.

6. In an automatic musical instrument having the usual striker pneumatics and source of power, in combination, an action wind chest; expression governing means for establishing therein varying degrees of tone intensity; a regulator for naintaining the varying degrees so establishedat a constant level whether one or many notes be sounded: and additional means connected to said wind chest to withdraw air from the wind chest when the tension falls below the lowest tension which the regulator is adjusted to maintain.

' 7. In an automatic musical instrument having the usual striker pneumatics and source ofpower, in combination, an action wind chest; a regulator; equalizing means controlling the tension in said wind chest, operative only wlienthe tension therein falls below the lowest tension which the regulator is'adjusted to maintain; and means for maintaining a constant tension in said equalizing means when operative. v

8. In an automatic musical instrument having the usual striker pneumatics and source of power, in combination, an action wind chest; a regulator; and a pneumatic connected to said wind chest; means for tensioning said pneumatic; means for adjusting said tensioning means to a point such that said pneumatic will tend to open when the tension in the wind chest falls below the lowest tension which the regulator is adjusted to maintain; and means for maintaining a constant tension n said pneumatic when open.

9. In an automatic musical instrument having the usual striker pneumatics and source of power, in combination, an action wind chest; a regulator; an equalizer in communication with said wind chest; means to exert upon said equalizer an opening force substantially equal to the closing force exerted by the lowest tension within said wind chest which said regulator is set to maintain; and means to maintain the opening force applied to said equalizer in all ositions of the equalizer at a level substantially equal to the closing force applied.

In testimony whereof, I have signed my name to this specification this 24th day of May, 1923.

CHARLES F. STODDARD. 

